Entries Tagged "feudal security"

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File Deletion

File deletion is all about control. This used to not be an issue. Your data was on your computer, and you decided when and how to delete a file. You could use the delete function if you didn’t care about whether the file could be recovered or not, and a file erase program—I use BCWipe for Windows—if you wanted to ensure no one could ever recover the file.

As we move more of our data onto cloud computing platforms such as Gmail and Facebook, and closed proprietary platforms such as the Kindle and the iPhone, deleting data is much harder.

You have to trust that these companies will delete your data when you ask them to, but they’re generally not interested in doing so. Sites like these are more likely to make your data inaccessible than they are to physically delete it. Facebook is a known culprit: actually deleting your data from its servers requires a complicated procedure that may or may not work. And even if you do manage to delete your data, copies are certain to remain in the companies’ backup systems. Gmail explicitly says this in its privacy notice.

Online backups, SMS messages, photos on photo sharing sites, smartphone applications that store your data in the network: you have no idea what really happens when you delete pieces of data or your entire account, because you’re not in control of the computers that are storing the data.

This notion of control also explains how Amazon was able to delete a book that people had previously purchased on their Kindle e-book readers. The legalities are debatable, but Amazon had the technical ability to delete the file because it controls all Kindles. It has designed the Kindle so that it determines when to update the software, whether people are allowed to buy Kindle books, and when to turn off people’s Kindles entirely.

Vanish is a research project by Roxana Geambasu and colleagues at the University of Washington. They designed a prototype system that automatically deletes data after a set time interval. So you can send an email, create a Google Doc, post an update to Facebook, or upload a photo to Flickr, all designed to disappear after a set period of time. And after it disappears, no one—not anyone who downloaded the data, not the site that hosted the data, not anyone who intercepted the data in transit, not even you—will be able to read it. If the police arrive at Facebook or Google or Flickr with a warrant, they won’t be able to read it.

The details are complicated, but Vanish breaks the data’s decryption key into a bunch of pieces and scatters them around the web using a peer-to-peer network. Then it uses the natural turnover in these networks—machines constantly join and leave—to make the data disappear. Unlike previous programs that supported file deletion, this one doesn’t require you to trust any company, organisation, or website. It just happens.

Of course, Vanish doesn’t prevent the recipient of an email or the reader of a Facebook page from copying the data and pasting it into another file, just as Kindle’s deletion feature doesn’t prevent people from copying a book’s files and saving them on their computers. Vanish is just a prototype at this point, and it only works if all the people who read your Facebook entries or view your Flickr pictures have it installed on their computers as well; but it’s a good demonstration of how control affects file deletion. And while it’s a step in the right direction, it’s also new and therefore deserves further security analysis before being adopted on a wide scale.

We’ve lost the control of data on some of the computers we own, and we’ve lost control of our data in the cloud. We’re not going to stop using Facebook and Twitter just because they’re not going to delete our data when we ask them to, and we’re not going to stop using Kindles and iPhones because they may delete our data when we don’t want them to. But we need to take back control of data in the cloud, and projects like Vanish show us how we can.

Now we need something that will protect our data when a large corporation decides to delete it.

This essay originally appeared in The Guardian.

EDITED TO ADD (9/30): Vanish has been broken, paper here.

Posted on September 10, 2009 at 6:08 AM • View Comments

Cloud Computing

This year’s overhyped IT concept is cloud computing. Also called software as a service (Saas), cloud computing is when you run software over the internet and access it via a browser. The Salesforce.com customer management software is an example of this. So is Google Docs. If you believe the hype, cloud computing is the future.

But, hype aside, cloud computing is nothing new . It’s the modern version of the timesharing model from the 1960s, which was eventually killed by the rise of the personal computer. It’s what Hotmail and Gmail have been doing all these years, and it’s social networking sites, remote backup companies, and remote email filtering companies such as MessageLabs. Any IT outsourcing—network infrastructure, security monitoring, remote hosting—is a form of cloud computing.

The old timesharing model arose because computers were expensive and hard to maintain. Modern computers and networks are drastically cheaper, but they’re still hard to maintain. As networks have become faster, it is again easier to have someone else do the hard work. Computing has become more of a utility; users are more concerned with results than technical details, so the tech fades into the background.

But what about security? Isn’t it more dangerous to have your email on Hotmail’s servers, your spreadsheets on Google’s, your personal conversations on Facebook’s, and your company’s sales prospects on salesforce.com’s? Well, yes and no.

IT security is about trust. You have to trust your CPU manufacturer, your hardware, operating system and software vendors—and your ISP. Any one of these can undermine your security: crash your systems, corrupt data, allow an attacker to get access to systems. We’ve spent decades dealing with worms and rootkits that target software vulnerabilities. We’ve worried about infected chips. But in the end, we have no choice but to blindly trust the security of the IT providers we use.

Saas moves the trust boundary out one step further—you now have to also trust your software service vendors—but it doesn’t fundamentally change anything. It’s just another vendor we need to trust.

There is one critical difference. When a computer is within your network, you can protect it with other security systems such as firewalls and IDSs. You can build a resilient system that works even if those vendors you have to trust may not be as trustworthy as you like. With any outsourcing model, whether it be cloud computing or something else, you can’t. You have to trust your outsourcer completely. You not only have to trust the outsourcer’s security, but its reliability, its availability, and its business continuity.

You don’t want your critical data to be on some cloud computer that abruptly disappears because its owner goes bankrupt . You don’t want the company you’re using to be sold to your direct competitor. You don’t want the company to cut corners, without warning, because times are tight. Or raise its prices and then refuse to let you have your data back. These things can happen with software vendors, but the results aren’t as drastic.

There are two different types of cloud computing customers. The first only pays a nominal fee for these services—and uses them for free in exchange for ads: e.g., Gmail and Facebook. These customers have no leverage with their outsourcers. You can lose everything. Companies like Google and Amazon won’t spend a lot of time caring. The second type of customer pays considerably for these services: to Salesforce.com, MessageLabs, managed network companies, and so on. These customers have more leverage, providing they write their service contracts correctly. Still, nothing is guaranteed.

Trust is a concept as old as humanity, and the solutions are the same as they have always been. Be careful who you trust, be careful what you trust them with, and be careful how much you trust them. Outsourcing is the future of computing. Eventually we’ll get this right, but you don’t want to be a casualty along the way.

This essay originally appeared in The Guardian.

EDITED TO ADD (6/4): Another opinion.

EDITED TO ADD (6/5): A rebuttal. And an apology for the tone of the rebuttal. The reason I am talking so much about cloud computing is that reporters and inverviewers keep asking me about it. I feel kind of dragged into this whole thing.

EDITED TO ADD (6/6): At the Computers, Freedom, and Privacy conference last week, Bob Gellman said (this, by him, is worth reading) that the nine most important words in cloud computing are: “terms of service,” “location, location, location,” and “provider, provider, provider”—basically making the same point I did. You need to make sure the terms of service you sign up to are ones you can live with. You need to make sure the location of the provider doesn’t subject you to any laws that you can’t live with. And you need to make sure your provider is someone you’re willing to work with. Basically, if you’re going to give someone else your data, you need to trust them.

Posted on June 4, 2009 at 6:14 AM •

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Sidebar photo of Bruce Schneier by Joe MacInnis.